SHARING THE EARTH : At last, war-weary environmentalists and developers are learning to work together to preserve endangered species.

More than 20 years after a 3-inch perch called the snail darter stalled construction on a $137-million Tennessee dam, today’s growing herd of endangered species, from foxes to phlox, is just as unpopular with builders and their bankers. It’s not hard to see why.

Southern California developers and state and federal agencies expect to pay more than $100 million for the land to protect what all parties refer to as the K-rat, the endangered Stephens’ kangaroo rat. Others have recently seen the once wide-ranging desert tortoise given emergency listing as an endangered species.

A battle-toughened establishment of home builders, landowners, slow-growth advocates, environmentalists, urban planners, lawyers, hydrologists, biologists and assorted other consultants sees combat daily over the future of the brown hills and green glens of California. And many of those struggles hinge on the fate of the state’s growing gallery of endangered, threatened and rare living things, which now number 254 sheep, salamanders, grasses, thistles and the like, with hundreds more waiting in the wings. Beyond this, the federal Fish and Wildlife Service has its own list, which includes 62 species in California alone.

Developers have long yearned to be rid of the endangered species laws. Now, for long-debated environmental reasons, and with some misgivings, many conservationists working with scarce species may be willing to give developers much of what they want.

The move is toward habitat conservation planning, which holds that the best way to save scarce species and accommodate reasonable development, is with broad, whole-habitat preserves that may involve groups of developments, collections of rare beasts and plants, and fewer but larger tracts of land. Piecemeal setting-aside of land has often created preserves that are too small for the species, or that ignore the interconnection of various species.

In fact, endangered species often appear in clusters. The pressures of growing cities, for instance, often affect many organisms at once. Environmentalists now speak in terms of preserving healthy communities, not just single beasts in islands of habitat.

Larger wildlife preserves also solve the problems of home range. The Florida panther, for instance, needs more room to roam than was realized when various small patches of land were first set aside for it. Each species may also have a minimum requirement to support enough individuals to keep a healthy gene pool. Now Florida conservationists are going back to set aside corridors of land to connect the smaller panther preserves.

Many developers are ready for the habitat conservation approach. Long resigned to endangered-species expenditures as part of the cost of doing business, they welcome the chance to consolidate their problems with rare bugs and plants and to be able to plan with greater certainty. Disruptive lawsuits under the endangered species acts often enter the picture late in the day, when the meter is running on a developer’s construction loans.

The classic example of habitat conservation planning was also the first in the country.

In the early 1980s, developers were poised to build on San Bruno Mountain, the last large open space on the San Francisco peninsula. Of 3,000 acres, the builders agreed to set aside 2,000 as open space and for recreation. It wasn’t until then that the endangered Mission blue butterfly turned up--over the entire 1,000 acres.

Under endangered-species law, this stopped the bulldozers cold. Even the accidental killing of a butterfly would bring automatic, and heavy, financial penalties. But in light of the earlier dedication of so much land to open space, this seemed unfair in the extreme. A San Mateo County supervisor set about to change the rules.

The upshot was an agreement among the several landowners and developers, the County of San Mateo, three cities, two state agencies, the local environmental lobby and the federal Fish and Wildlife Service to design the development to protect some 20 species--not only the butterfly but also such endangered species as the San Francisco garter snake and scarce organisms not yet officially listed. Several hundred more acres were set aside as preserve.

But since the planning was done early enough in the game, developers lost not one of their 3,000 planned houses in the deal. More to the point, the resulting amendment to the federal endangered species law ended developers’ liability, when they agreed to this kind of multi-species protection, for accidental deaths. They could build without interference on the rest of the land.

“No one is saying we’re going to walk away from using the endangered species laws,” cautioned Richard Spotts, California representative of Defenders of Wildlife. “This is more taking us to a higher level, if you will. . . . People have seen this coming for a long time now, looking at systems instead of individual parts of the system.”

Nor are calm and reason about to arrive in the exploding Southern California housing tracts. While such habitat conservation plans may be in the works for the Stephens’ kangaroo rat, they are still the exception. And absent such sometimes-tricky agreements, environmentalists are still likely to resort to their safety net, the endangered species laws. With predictable opposition.

“About two weeks ago I saw a new map that just came out, on protecting the desert tortoise,” said an unhappy Mel Wynn, president of the Building Industry Assn. of Southern California. “And the map showed the endangered species area running from the Antelope Valley all the way to Las Vegas, and all the area in between, a huge amount of ground. . . . That’s pretty scary.”

“I sound like a real redneck,” Wynn continued, “but I just see somebody sitting down and saying, ‘Now, how can we stop these guys from developing?’ And this was the brainstorm.”

“We’re not all looking under rocks for endangered species,” countered an exasperated Jill Swift, president of Friends of Caballero Canyon and a longtime Sierra Club activist. “We’re working for something that our kids and grandchildren will savor and enjoy, instead of a 20-story condominium that’s about to be torn down because it was built so poorly.”

In fact, these scarce species have become sophisticated and powerful weapons, wielded by developers and environmentalists alike.

Some developers now use the presence of an endangered species to bargain-down the price of land, arguing to landowners that their costs will be higher to build on that site.

For their part, slow-growth advocates and environmentalists have found an uncompromising legal tool in obscure flora and fauna found nesting in the path of progress. Not only do endangered species laws disregard how much it costs a developer to preserve a rare grass or spotted owl, once they are discovered on a project, they move the battle from the political and to the judicial arena, where environmentalists have often been more successful, not being pitted against expensive lobbying campaigns.

With the endangered species laws looming in the background, some builders will try to reach accommodation even before a battle develops.

Take the case of the newly found Riverside fairy shrimp, an animal which developers are likely to save before it is declared endangered; before, in fact, it has even been officially declared a separate species.

Don’t get out the cocktail sauce. The size of a cashew, this flimsy crustacean lives its brief, quiet life swimming upside down in as few as five small ponds in Riverside County, ponds that exist for a matter of weeks, or at most months, after the first big winter rains. The Riverside version is most easily distinguished from the 16 other species of fairy shrimp in California by the male’s head appendages--large for its kind--which are used to grasp female shrimp during mating. They eat bacteria and are in turn eaten by wading and migratory birds.

Clyde Eriksen, a bushy-browed ecologist and biology professor at the Claremont Colleges, has been studying fairy shrimp for 35 years. He was “dragged onto the environmental side” when his wife was sprayed with malathion, the same pesticide used against the Mediterranean fruit fly, two decades ago. A breeze wafted the spray onto her sewing porch as municipal workers debugged a nearby tree. When she complained, the men told her: “Oh, that’s all right, lady. This isn’t potent stuff at all. Just wait. In two weeks, that oak tree across the street? We’re going to come back and spray that with DDT.”

Five years ago, Clyde Eriksen joined Denton Belk, a world-renowned fairy shrimp expert from Texas, and Larry Eng, a shrimp researcher himself and an endangered species specialist for the California Department of Fish and Game, to conduct a survey of the state’s fairy shrimp population.

They studied all the embalmed collections that they could find, as well as fresh samples from sites around the state. Under the microscope they discovered what they considered to be four new species, including the Riverside shrimp. Eriksen also soon discovered that the only significant remaining pool in which the shrimp lived, called Skunk Hollow, was about to become part of Rancho Bella Vista, a development with more than 2,500 master-planned homes.

Eriksen wrote to a Riverside County supervisor pleading that his new shrimp, and the endangered California orcutt grass found on the same site, “not be lightly wiped from the face of the earth.” The Sierra Club rolled out its siege guns and the board of supervisors demanded a plan to save the Riverside fairy shrimp.

Meanwhile, to the casual eye, the Skunk Hollow pool most of the time is a dry depression of slightly darker grasses in a farmed area of roughly a hundred acres. One proposal from the first developer was to physically transport Skunk Hollow somewhere else.

Michael Packard, president of Lane/Kuhn Pacific Communities, which bought the Skunk Hollow site in January, this time naming the project MountainView, knew that the rare crustacean was there. But Packard hasn’t wasted a minute or a dollar arguing that the world could well do without the Riverside fairy shrimp.

“There’s enough question here,” said Packard one afternoon in his Escondido office, “that rather than fight . . . let’s just make the assumption that it is in fact worth preserving, endangered or not, and figure out the best way to accommodate that preservation.” Packard, seated at a conference table in the company of his attorney, admitted that he’s something of a new breed of builder.

“It’s been very easy for a long time to paint this industry as the black hats,” he said. “And I think to some extent our community has earned that distinction.

“And I think there is a heightening of awareness” among many developers today, Packard said. “But I don’t think you can ignore cost.”

“In some cases,” explained Lindell Marsh, the attorney, “the issue you’re dealing with is of a magnitude that one project owner really can’t adequately address it. . . . When you have a species over an extended range, that’s a real problem.”

This is the sort of vexation that all sides hope broad habitat conservation plans can solve.

As it happens, Marsh is also the driving force behind what are known as the Starr Ranch discussions, a series of meetings over the past few years that were first held at the Audubon Society’s Starr Ranch Preserve in Orange County. At these, environmentalists, planners, developers, public regulators and scientists attempt to develop ways to ease the friction between Southern California developers and their opponents. Habitat conservation plans are central to their discussions.

“And I think that at least with the big land developers, government agencies and environmentalists,” said Marsh, holding his thumb and forefinger slightly apart, “we’re that close to basic agreement.”

“As conservationists, we’re sort of offering the olive branch,” agreed Richard Spotts, of Defenders of Wildlife.

Still, environmentalists want to move with caution.

Michael Bean, a Washington-based senior attorney with the Environmental Defense Fund who has been a central figure in endangered species law for more than a dozen years, thinks that most conservationists favor the new plans, though some remain ardently opposed. Critics worry that developers can bring much greater economic resources than can nonprofit environmental groups to these complicated planning scenes. Habitat conservation planning may take a year or more of committee work and reports.

“I don’t think anyone disagrees with the potential of these habitat plans to be very useful,” said Bean, who supports them. But he worries that most so far have been largely dominated by the developers. “The question left open . . . is whether they give away more than they should give.”

Nona Yates, in the Times library, assisted with the research for this article.

SPECIES AT THE BRINK 1 FAIRY SHRIMP A typical fairy shrimp. The Riverside variety was discovered so recently that no drawing exists. It has yet to be declared a new species, let alone endangered. But the shrimp is so rare that the owner of the largest pond where it lives has agreed to cooperate with environmentalists to protect it. 2 DESERT TORTOISE The California desert tortoise, whose population has dropped by as much as 60% in some areas, was given emergency listing as an endangered species in July. 3 KANGAROO RAT The Stephens’ kangaroo rat was placed on the federal endangered species list in October, 1988. Some 27 square miles of Riverside County may be set aside to preserve its habitat.